In any modern power tool or home appliance, a collector motor is used. This is due to their versatility, i.e. ability to work from both AC and DC voltage. Another advantage is the effective starting point.
However, the high frequency of revolutions of the collector engine does not suit all users. For a smooth start and the ability to change the frequency of rotation was invented regulator, which is quite possible to make their own hands.
- 1 The principle of operation and types of collector engines
2 Regulator device
- 2.1 Standard device
- 2.2 Modified Schemes
- 2.3 Video: device speed control with maintaining power
- 3 Overview of Typical Patterns
- 4 How to do it yourself
The principle of operation and types of collector engines
Each electric motor consists of a collector, a stator, a rotor and brushes. The principle of its operation is quite simple:
- Current is fed to the stator and the rotor connected to each other.
- Formed magnetic field.
- Due to the effect of magnetic stress, the rotor begins to rotate.
- Brushes (usually made of graphite) transfer the voltage to the rotor.
- When changing the direction of the current in the stator or rotor, the shaft rotates in the other direction.
In addition to the standard device also exist:
- Serial excitation motors - are more resistant to overloads (most often used in home appliances).
- Products of parallel excitation - have a greater number of turns and a small resistance.
- Single-phase motors - ease of manufacture and a wide range for use, but low efficiency.
In the world there are many schemes of such devices. Nevertheless, all of them can be divided into 2 groups: standard and modified products.
Typical products are easy to manufacture idistor, good reliability when changing engine speed. As a rule, such models are based on thyristor controllers. The principle of operation of such schemes is quite simple:
- The charge goes to the capacitor.
- Through the variable resistor goes the breakdown voltage Dinistor.
- Further he "makes the way".
- "Opens" the triac, which is responsible for the load.
- The higher the voltage, the more often the triac will open.
Thus, the adjustment of the speed of the collector engine. In most cases, a similar scheme is used in foreign domestic vacuum cleaners. However, you should know that such a speed controller does not have feedback. Therefore, when you change the load will have to adjust the speed of the motor.
Of course, the standard device suits many amateur speed regulators to “dig” in electronics. However, without progress and improvement of products, we would still live in the Stone Age. Therefore, more interesting schemes are constantly being invented, which many manufacturers are happy to use.
Rheostat and integral regulators are most commonly used. As the name implies, the first option is based on a rheostat circuit. In the second case, an integral timer is used.
Rheostat differ in efficiency in changing the number of revolutions of the collector engine. High efficiency due to the power transistors, which take part of the voltage. In this way, the flow of current is reduced and the motor runs with less diligence.
Video: device speed control with maintaining power
The main disadvantage of this scheme is the large amount of heat generated. Therefore, for smooth operation, the regulator must be constantly cooled. While cooling the device should be intense.
Another approach is implemented in the integral controller, where the integral timer is responsible for the load. As a rule, in such circuits are used transistors of almost any names. This is due to the fact that in the composition there is a microcircuit possessing large values of the output current.
If the load is less than 0.1 amps, then all the voltage goes directly to the chip, bypassing the transistors. However, for the regulator to work effectively, it is necessary that the gate has a voltage of 12V. Therefore, the electrical circuit and the voltage of the power supply itself must correspond to this range.
Overview of Typical Patterns
It is possible to regulate the rotation of the shaft of a low-power electric motor by means of a series connection of a power resistor with no. However, this option has a very low efficiency and the absence of the possibility of a smooth change in speed. To avoid this trouble, you should consider several schemes regulator, which are used most often.
Features of the first option:
- The PWM transistor has a sawtooth generator with a frequency of 150 Hz.
- In the role of the comparator is an operational amplifier.
- To change the speed using a variable resistor that controls the duration of the pulses.
As is known, PWM has a constant amplitude of pulses. In addition, the amplitude is identical to the supply voltage. Consequently, the electric motor will not stop, even at low speeds.
The second option is similar to the first. The only difference is that an operational amplifier is used as a master oscillator. This component has a frequency of 500 Hz and is engaged in the development of pulses having a triangular shape. Adjustment is also carried out by a variable resistor.
How to do it yourself
If you do not want to spend money on the purchase of a finished device, you can make it yourself. Thus, you can not only save money, but also gain useful experience. So, for the manufacture of thyristor controller will need:
- soldering iron (for performance testing);
- thyristor, capacitors and resistors;
As can be seen from the diagram, the regulator controls only 1 half period. However, for testing the performance of a regular soldering iron this will be quite enough.
If knowledge of decoding the scheme is not enough, you can familiarize yourself with the text version:
- The mains supply goes to the capacitor.
- The capacitor gets full charge and starts working.
- The load is transferred to the lower cable and resistors.
- A thyristor electrode is connected to the positive contact of the capacitor.
- One sufficient charge voltage
- The second semiconductor opens.
- Thyristor passes through the load received from the capacitor.
- The capacitor discharges and repeats a half period.
The use of regulators allows more economical use of electric motors. In certain situations, such a device can be made independently. However, for more serious purposes (for example, control of equipment for heating) it is better to purchase a finished model. Fortunately, there is a wide choice of such products on the market, and the price is quite affordable.